The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
The special demands on the controllability of friction clutches are present both with respect to the precision of the setting of a specific torque and with respect to the speed of the control. The latter in particular on the release of the clutch, for instance on an ABS intervention or an ESP intervention. Furthermore, the electric motor should use as little energy as possible over all, that is it should also only run when necessary. There is also the demand for intrinsic safety. This means that the most secure state (usually that is the released clutch) should be adopted automatically in the event of system failure.
These demands also require an embodiment of the actuator in accordance with the preamble of the first claim, such as is, for example, the subject matter of WO 2004/040158 A2 of the applicant. Further details can be seen from this. An actuator of this type is cost-effective because the control valves required with conventional actuators can be dispensed with. The control of the electric motor for the actuation of the actuator is, however, demanding from a technical control viewpoint and is the subject of the present invention, which can be used independently of the specific construction and of the control of the electric motor itself.